Field of the Invention
The present invention relates to a method for producing a fiber-reinforced resin bonded body, for bonding composite members each containing a thermoplastic resin and discontinuous fibers to obtain a fiber-reinforced resin bonded body.
Description of the Related Art
Studies have been made on fiber-reinforced resins usable in car body components and the like for the purpose of weight reduction, strength increase, etc. Among the fiber-reinforced resins, particularly fiber-reinforced thermoplastic resins (FRTPs) have attracted much attention. The FRTP contains as a base material a thermoplastic resin, which can be more easily shaped in a shorter time than thermosetting resins. In a composite member composed of the FRTP, the thermoplastic resin used as the base material can be melted by heating. Therefore, separately produced composite members composed of the FRTP can be easily weld-bonded to each other. Consequently, a fiber-reinforced resin bonded body can be produced by bonding a plurality of the composite members to each other, and thus even a large car body component can be easily produced at low cost.
In this case, substantially uniformly distributing reinforcing fibers intertwined with each other in a connection between the composite members in the weld bonding process is considered as one way to improve the bonding strength of the composite members and thus the mechanical properties of the fiber-reinforced resin bonded body.
For example, a method for weld-bonding such composite members is proposed in Japanese Laid-Open Patent Publication No. 11-090986. In this weld bonding method, connection ends of a first composite member and a second composite member are overlapped with each other, and contact surfaces of the composite members are bonded to each other, so that a connection is formed to produce a fiber-reinforced resin bonded body. Specifically, first, connection surfaces at the connection ends of the composite members are heated to melt the thermoplastic resin, whereby the reinforcing fiber is partially exposed on the connection surfaces. Then, the connection ends are overlapped with each other in such a manner that the connection surfaces are brought into contact with each other, and the composite members are press-formed and weld-bonded. As a result, the reinforcing fibers are intertwined with each other and substantially uniformly distributed in the connection between the overlapped connection ends in the produced fiber-reinforced resin bonded body.